I am expected this to give 'correct'. Running this in a PHP script on my local server and here returns 'wrong'. Running the same logic here returns 'correct'? Can anyone help explain what is going on? Or maybe I am wrong to expect 'correct' to be echoed?

I found a pattern which uses an assertion instead of the look-behind. There is alternation as well, but I bet that could be factored into the assertion with someone a little more REGEX talented than I...